Prepare the yeast dough (see Easter yeast plait), but separate the egg. Set aside the egg white for the filling and use only the egg yolk for the dough. Let the dough rise once.
For the nut filling, coarsely grate the marzipan. Knead with egg white, ground nuts, 50 g sugar, vanilla sugar, 1 pinch of salt, 1 teaspoon cinnamon, cocoa and cream.
Grease the springform pan (26 cm Ø). Knead the dough again on a floured work surface and roll out to a rectangle (approx. 35 x 40 cm). Spread with nut mixture. Cut into 6 strips (each approx. 40 cm long).
Roll up the strips and place them in the middle of the mould. Wrap the remaining strips around it in a spiral. Leave to rise again for another 15 minutes.
Preheat oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer). Coarsely chop the nuts. Whisk egg yolk and 2 tbsp. milk, brush the snail with it. Sprinkle with nuts. Bake in hot oven for 25-30 minutes.
Stir 2 tablespoons of sugar, 1⁄2 tsp. cinnamon and 2 tablespoons of water. Approx. 5 minutes before the end of the baking time, sprinkle the cake with it. Take out and let it cool down.